Field of the Invention
The present invention relates to a robot cleaner and a method for controlling the same, and more particularly to a robot cleaner which is capable of climbing a high stepped portion and a method for controlling the same.
Discussion of the Related Art
In general, a vacuum cleaner is an apparatus which suctions in external air containing foreign substances and then separately collects the foreign substances, by driving an air suction unit provided in the cleaner body to generate air suctioning force.
Vacuum cleaners performing the functions as above are classified into manual vacuum cleaners, which are directly manipulated by a user, and robot cleaners which autonomously perform cleaning operation without manipulation by the user.
The robot cleaner suctions foreign substances such as dust from the floor, autonomously traveling in the area to be cleaned. In other words, the robot cleaner automatically performs cleaning of a certain area. To this end, the robot cleaner is provided with a distance sensor to sense a distance from an obstacle such as furniture, office supplies, or a wall in the area to be cleaned, and left and right wheels for movement of the robot cleaner. Here, the left and right wheels are respectively configured to be rotated by a left wheel motor and a right wheel motor. According to operation of the left wheel motor and the right wheel motor, the robot cleaner autonomously performs indoor cleaning, changing travel direction.
In addition, the robot cleaner is provided, at a lower portion thereof, with a suction nozzle to suction foreign substances from the floor. The suction nozzle includes a nozzle case fixed to the body of the cleaner so as not to be moved, a suction inlet formed on the bottom of the nozzle case to suction foreign substances, and an agitator rotatably arranged at the suction inlet to gather foreign substances such as dust accumulated on the floor to the suction inlet.
In addition to the left and right wheels, which are usually electrically driven, the robot cleaner is further provided with a caster allowing smooth rotating motion of the robot cleaner.
According to the conventional technology described above, when the robot cleaner climbs up the threshold abruptly rising from a lower position to a higher position or enters a carpet, the driving force for the left and right wheels and the frictional force between the left and right wheels and the surface may be insufficient to climb up an encountered stepped portion depending on the height of the stepped portion, and thereby the robot cleaner may fail to climb up the stepped portion.
Particularly, while the robot cleaner needs to be capable of climbing up a stepped portion having a great difference in height between the upper and lower sides of the stepped portion such as the threshold, but the robot cleaner often fails to climb. As a result, the space on the opposite side of the threshold is not cleaned.